A Milestone in RSV Prevention: FDA Approves Pfizer's Abrysvo Vaccine for Older Adults

Last night, Pfizer Inc. announced the US Food and Drug Administration (FDA) approved their respiratory syncytial virus (RSV) vaccine, Abrysvo, for older adults. This approval allows the use of Abrysvo in individuals aged 60 years and older to prevent lower respiratory tract disease caused by RSV.

Abrysvo, Pfizer's bivalent RSV prefusion F (RSVpreF) vaccine, is composed of 2 preF proteins specifically chosen to optimize protection against RSV A and B strains. With this approval, the FDA indicates all available trial data has proven Abrysvo to be safe and effective.

“A vaccine to help prevent RSV had been an elusive public health goal for more than half a century," stated Annaliesa Anderson, PhD, senior vice president and chief scientific officer of vaccine research and development at Pfizer. “Abrysvo will address a need to help protect older adults against the potentially serious consequences of RSV disease. We are extremely grateful to the clinical trial participants, study investigator teams and our dedicated Pfizer colleagues for their roles in making this vaccine available.”

In the more than 50 years of working to develop an RSV vaccine, Abrysvo is the world’s second-ever to be granted approval. Last month, GSK’s Arexvy (RSVPreF3 +AS01E) was approved to prevent lower respiratory tract disease (LRTD) caused by RSV in adults 60 years and older.

The FDA's decision to approve Abrysvo as well was based on data obtained from the pivotal Phase 3 clinical trial (NCT05035212) known as RENOIR (RSV vaccine Efficacy study iNOlder adults Immunized against RSV disease). RENOIR is a global, randomized, double-blind, placebo-controlled study designed to evaluate the efficacy, immunogenicity, and safety of a single dose of the vaccine in adults aged 60 and older.

Approximately 37000 participants were enrolled in RENOIR, with half receiving RSVpreF 120 μg and the other half receiving placebo in a 1:1 ratio. RENOIR is an ongoing study, with efficacy data being collected during the second RSV season.

Edward E. Walsh, MD, Professor of Medicine at the University of Rochester Medical Center and principal investigator of the RENOIR trial, commented, "This past RSV season demonstrated the serious consequences and potential health risks this virus poses for older adults. Today’s FDA approval of Abrysvo recognizes significant scientific progress, and importantly helps provide older adults potential protection against RSV and an opportunity to improve community health by helping prevent the disease.”

RSV is a contagious virus that commonly causes respiratory illnesses worldwide. It primarily affects the lungs and breathing passages, often leading to severe illness or even death. In the US, RSV poses a considerable burden on older adults, with disease severity increasing with age and comorbidities such as chronic obstructive pulmonary disease, asthma, and congestive heart failure.

In most healthy individuals, RSV manifests with mild, cold-like symptoms. Most people recover within 2 weeks, often without knowing they had contracted RSV. Infants and young children, however, are also susceptible to the worst of RSV infection. Thus, Pfizer is also seeking approval to administer RSVpreF to pregnant persons, with the goal of preventing medically attended lower respiratory tract disease (MA-LRTD) and severe MA-LRTD caused by RSV in infants from birth to 6 months of age.

The maternal vaccine was recently recommended for approval by the FDA’s Vaccines and Related Biological Products Advisory Committee (VRBPAC), and a decision is expected by August 21, 2023.

Regarding the use of RSV vaccines in older adults, the US Centers for Disease Control and Prevention's (CDC) Advisory Committee on Immunization Practices (ACIP) is scheduled to meet on June 21, 2023, to discuss recommendations. Pending the outcome of this meeting, Pfizer expects Abrysvo to be available in the third quarter of 2023, just ahead of the anticipated RSV season this fall.

In addition to this recent approval, Pfizer reported positive top-line results earlier this month from a Phase 3 study that evaluated the safety and immunogenicity of Abrysvo coadministered with seasonal inactivated influenza vaccine (SIIV) in adults aged 65 and older.

Furthermore, Pfizer announced its plans to conduct multiple clinical trials evaluating RSVpreF in healthy children aged 2-5 years, children aged 5-18 years with comorbidities, adults aged 18-60 years with comorbidities, and adults aged 18 years and older who are immunocompromised and at high risk for adverse RSV outcomes.

Contagion is actively following all developments in the RSV space. Return soon for updates, or click here to browse our past breaking news coverage and interviews with lead researchers.